The use of solar energy to help solve the world's present energy crisis is appealing. There is a large quantity of such energy which is available for use without any accompanying adverse environmental impact. However, solar energy is diffuse, i.e., it is spread over a wide area and the amount of energy available per square foot is not very large. Additionally, if the solar energy is to be used effectively, it must be received while the sun is shining and stored for use on cloudy days and at nighttime.
The storage of heat from solar energy has presented difficulties in the past. Various proposals have been advanced including hot water which is stored in insulated tanks, molten salts which deliver their heat of fusion while crystallizing, and basements full of hot rocks which are warmed during the day for use in warming the air during the night. The general idea has centered around the provision of storage sufficient for a daily or a weekly cycle to meet the needs for one house or building. However, storage in this manner has been found to be expensive. When heat is most needed, i.e., winter, the least amount of energy is received from the sun. The same type of situation exists with respect to cooling efforts. When cooling is most needed, i.e., summer, the least amount of sources for coolness is available.
In addition to single-building energy requirements, the need exists for a year-round solar heating and cooling system for use by a city, town or other large-scale energy consumer. Little attention has been directed to such large-scale needs, the satisfaction of which offers significant potential not heretofore appreciated.
Applicant presently is aware of existing patents in the field of the art, including U.S. Pat. No. 3,620,206 (Harris, et al., 1971); U.S. Pat. No. 3,339,629 (Hervey, 1967); U.S. Pat. No. 2,693,939 (Marchant, et al., 1954); U.S. Pat. No. 2,780,415 (Gay, 1957); U.S. Pat. No. 2,584,573 (Gay, 1952); U.S. Pat. No. 2,007,406 (Miller, 1935); U.S. Pat. No. 2,637,531 (Davidson, 1953); U.S. Pat. No. 3,262,493 (Hervey, 1966); and the reeferences cited therein. Applicant also is aware of the article by Charles F. Meyer and David K. Todd, entitled "Conserving Energy With Heat Storage Wells", in 7 Environmental Science & Technology 512 (1973).